Multiple chamber induction furnace



Sept. 3, 1957 K. A. LANG MULTIPLE CHAMBER INDUCTION FURNACE Filed Nov. 14, 1955 11w NTOR.

BY @Mumm ATTORNEYS.

United States Patent MULTIPLE CHAMBER INDUCTION FURNACE Karl A. Lang, Glenview, Ill., assignor to Lindberg Engineering Company, Chicago, 111., a corporation of Illinois Application November 14, 1955, Serial No. 546,521

3 Claims. (Cl. 13-29) This invention relates to multiple chamber induction furnaces and more particularly to induction furnaces for melting and holding metal. In my co-pending application Serial No. 480,755, filed January 10, 1955, there is disclosed and claimed a multiple chamber furnace in which the heat input to the different chambers is individually controlled. The present invention relates to a furnace of the same type and has for one of its objects a simplification of the construction of such a furnace.

Another object of the present invention is to provide an induction furnace in which two secondary loops have one leg in common, thus simplifying and reducing the cost of construction and making the furnace more compact.

A further object is to provide a furnace in which the chambers and secondary loop channels are formed in a continuous body or liner of refractory material.

According to one feature of the invention the chambers and channels are rammed simultaneously with refractory cement or the like to provide a continuous integral surface.

The above and other objects and features of the invention will be more readily apparent from the following description when read in connection with the accompanying drawing, in which:

Figure 1 is a side elevation of a furnace embodying the invention;

Figure 2 is a horizontal section on the line 2-2 of Figure 1; and

Figure 3 is a vertical section on the broken line 3-3 of Figure 2.

The furnace as shown comprises an outer casing or shell formed of metal such as steel to provide a support for the body in which the furnace chambers are formed. The shell has a lateral extension 11 also formed of metal such as steel and interrupted intermediate its ends by an insulating strip 12 to interrupt flow of current through the shell. As shown, the shell 11 extends horizontally outward from one side of the main shell 10 intermediate the top and bottom thereof and is of less height than the main shell.

The shell structure contains a lining which may be formed as shown of strips or blocks of refractory material such as firebrick or the like shown at 13 and substantially covering the inner surface of the shell. Within the lining a second lining or body of refractory material 14 is supported and is molded to form a pair of spaced chambers 15 and 16 and melting loop channels, as described hereinafter, communicating therewith. In forming the lining or body 14, removable forms may be inserted for the chambers and channels and refractory cement may be rammed in around the forms to produce a single integral liner for the chambers and channels. In the case of the channels the forms may be formed of combustible material such as wood, metal, or the like, which can be burned out or melted during firing of the lining after the refractory cement has been rammed.

In the completed rammed structure the two chambers 15 and 16 communicate through a submerged passage or opening 17 which is of relatively restricted size compared to the cross section of the chambers. Metal may flow through this passage or opening between the chambers.

The chamber 15 is formed in one side with a flared groove 18 extending across the major part of its length through which it communicates with the melting channels. The melting channels as shown at 19 and 21 are arcuately shaped to form a secondary loop having the general configuration of an elongated oval. The legs 19 and 21 communicate with spaced points in the flared groove 18 and are joined remote from the chamber 15 in a widening channel section 22 which preferably opens through the outer Wall of the shell 11, as shown at 23. The opening 23 is desirable for burning out the forms and for firing the lining. In use, this opening is closed by a ceramic plug 24 held in place by a strap 25 bolted or otherwise secured to the outer wall of the shell 11.

The secondary loop formed by the channels 19 and 21 is threaded by a primary uni-t including a closed rectangular magnetic core 26 having one leg extending through an opening 27 in the center portion of the loop. A suitable winding 30 is placed on the core, within the opening 27, to be energized by alternating current to induce flow of melting current through the metal in the loop.

To form the opening 27 the top and bottom sheets of the shell 11 are cut out and a sleeve 28 which is preferably of metal is inserted and secured in place. The sleeve is preferably formed with a gap 29 to interrupt flow of induced current therethrough when the primary is energized.

A second loop communicating with the chambers 15 and 16 is provided by a curved channel 31 formed in the body 14 communicating at one end through a flared opening 32 with the chamber 16. The channel 31 is connected through a short channel portion 33 with the channel 21 at a point spaced from the chamber 15 and is provided with an opening 34 at the outer face of the shell 11 which is closed by a ceramic plug 35. The secondary loop formed by channels 31, 33 and a portion of channel 21 has current flow induced therein by a primary unit, including a core 36 extending through an opening 37 between channels 21 and 31 and carrying a winding 40 to be energized by alternating current. The opening 37 is defined by a sleeve 38 formed with a gap 39 therein to interrupt current flow therethrough.

In this construction the first secondary loop formed by the channels 19 and 21 communicates only with the chamber 15 so that all of the heat supplied by the first secondary loop will go into the chamber 15 which is preferably the melting chamber. Heat produced by the secondary loop formed by the channels 31, 33 and 21 will be divided between the chambers 15 and 16. By regulating the current supplies to the two primary units the relative quantities of heat supplied to the chambers 15 and 16 can be accurately controlled so that when relatively cold metal is charged in the chamber 15 it will be melted quickly without chilling the metal in chamber 16 or without resulting in overheating of the metal in chamber 16.

Since the two chambers and the channels are formed in a single refractory body or liner, possibility of leakage is eliminated and a very strong, compact construction is provided. Furthermore, since the channel 21 is common to the two secondary loops, the secondary loop structure can be made extremely compact and can be formed in a very simple manner.

While one embodiment of the invention has been shown and described in detail, it Will be understood that this is illustrative only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is: r

1. A multiple chamber induction furnace comprising a body formed with a pair of spaced chambers adapted to hold molten metal, a passage in the body connecting the chambers and lying below the level of molten metal therein, means defining a pair of interconnected channels forming an open loop connected at its ends to spaced points in one of the chambers, means defining a third channel connected at one end to one of said pair of channels at a point spaced from said one of the chambers and connected at its other end to the other chamber, a first primary threading the loop, and a second primary threading the third channel.

2. A multiple chamber induction furnace comprising a body formed With a pair of spaced chambers adapted to hold molten metal, a passage in the body connecting the chambers and lying below the level of molten metal therein, a loop structure projecting laterally from the chambers and formed with a generally U-shaped channel therein connected at its ends to spaced points in one of the chambers, a first primary threading the U-shaped channel, a second curved channel in the loop structure connected at one end to the U-shaped channel at a point spaced from said one of the chambers and connected at its other end to the other chamber, and a second primary threading the second channel.

3. A multiple chamber induction furnace comprising a metal shell having a lateral extension thereon, insulating means interrupting the shell of the extension to prevent current flow therethrough, a continuous lining of refractory material in the shell and the extension formed with a pair of spaced communicating chambers in the shell and a pair of secondary loops in the extension, both ends of one secondary loop communicating with one of the chambers and the two ends of the other loop communicating with the tWo chambers respectively and two primaries threading the loops respectively.

References Cited in the file of this patent UNITED STATES PATENTS Re. 22,948 Tama et al Dec. 9, 1947 761,920 Schneider June 7, 1909 1,031,257 Greene July 2, 1912 1,070,017 Crafts Aug. 12, 1913 1,660,209 Sasnett Feb. 21, 1928 2,503,621 Lindner et a1 Apr. 11, 1950 2,520,349 Tama Aug. 29, 1950 2,541,841 Tama Feb. 13, 1951 

